1. Field of the Invention
This invention relates to a recording and/or reproducing apparatus for flexible magnetic disks, wherein a disk cassette consisting of a cassette and a flexible sheet-like magnetic disk, such as microfloppy disk, accommodated in the cassette, is chucked and the magnetic disk in the disk cassette is rotationally driven for writing or reading information signals to or from the magnetic disk.
2. Related Art Statement
Heretofore, in a recording and/or reproducing apparatus for flexible magnetic disks, in which a disk cassette such as micro-floppy disk, is attached or mounted and the information signals are written to or read from the magnetic disk contained in the cassette, there is provided an enclosed a built-in disk attachment unit whereby the magnetic disk is chucked and secured to the disk table of the rotational driving device for the magnetic disk. The disk attachment unit is so designed that, as the disk cassette is introduced by way of the disk insertion and removable opening or aperture, the cassette holder is lowered for pressure holding of the disk cassette on the positioning pins while the magnetic disk is chucked on the disk table. The casette holder of the disk attachment unit operating in the above described manner is mounted with top of a loading plate slidably disposed on top of the chassis and, as the loading plate is slid on the chassis, the cassette holder is moved vertically up and down with respect to the chassis. The magnetic disk is chucked and attached onto the disk table as described above when the cassette holder is lowered with respect to the chassis.
In operative association with the lowering of the cassette holder, a supporting arm of the head unit carrying a magnetic head or a disk supporting pad at the distal end thereof is rotated into abutment on the magnetic disk. The magnetic head or the disk supporting pad at the distal end of the thus rotated supporting arm and another magnetic head at the distal end of the other supporting arm facing the aforementioned supporting arm are brought into sliding contact with the magnetic disk while clamping the disk therebetween so as to enable information signals to be written to or read from the disk.
When the loading plate is slid for floating the cassette holder, the disk is unchucked from the disk table while the disk cassette is ejected towards the disk insertion or removal opening.
In the above described conventional disk attachment unit, when the loading plate is slid to lower the cassette holder onto the disk table for chucking the magnetic disk in the cassette onto the disk table of the rotational driving device for the magnetic disk, the cassette holder is caused to descend horizontally onto the disk table. The supporting arm of the head device is also turned towards the magnetic disk in operative association with and nearly at the same time as the lowering of the cassette holder. The magnetic disk is clamped between the magnetic head or the disk supporting pad at the distal end of the supporting arm and the magnetic head at the distal end of the other supporting arms.
In the above described conventional disk attachment unit wherein the clamping of the magnetic disk by the head unit takes place almost concurrently with the lowering of the cassette holder holding the disk cassette, there is the risk that the magnetic disk may be clamped by the head unit prior to complete engagement of the center opening in the metallic center core secured to the magnetic disk by the spindle of the rotational driving unit of the magnetic disk. As a result, chucking of the magnetic disk onto the disk table is occasionally insufficient so that it may be impossible to drive the magnetic disk into rotation.
In order to prevent the occurrence of insufficient chucking as described above, it may be contemplated to chuck the magnetic disk by the head unit after the cassette holder is lowered onto the disk table. Thus it has been contemplated to provide rotation delay means whereby the supporting arm of the head unit is turned with a delay relative to the descent of the cassette holder. When the rotation delay device for the supporting arm is provided in this manner, the overall system is necessarily complicated, while the production costs are not lowered.